Sportsmen and women weight train to improve performance because, everything else being equal, a weight-trained muscle is more resilient and better able to generate force. There are numerous weight training systems on offer to coach and athlete, and their effects on promoting a specific fitness response are relatively well known. However, when it comes to the effects of different weight training systems on the endocrine system and hormone levels, this is not always the case. As John Shepherd explains, these weight-training induced hormonal changes have significant effects on muscle trainability and performance, and are also related to age, sex and workout intensity.

Weight training intensity, GH and muscle building

Charles Van Commenee (the coach of Olympic heptathlon gold medallist Denise Lewis) used to advocate the use of weight training sessions with heavy weights, in excess of 90% of 1 repetition maximum (1RM), in numerous sets (eight plus) using full recoveries. This was in stark contrast to the usual 70-80% of 1RM workouts, employing 68 fast movement repetitions over 3-6 sets – a staple workout for the sprinter/jumper type athlete.

Van Commenee’s reasoning was that the latter type of workout was more of a bodybuilder’s one – ie designed to produce an increased anabolic hormonal (particularly GH-producing) workout response, which would tend to build more muscle. He believed that the key relevance for the athlete was the power-to-weight ratio. According to Van Commenee, a higher intensity, greater GH- releasing workout might increase an athlete’s weight sufficiently to compromise performance. However, a heavier, low repetition workout, although developing all-important athletic power, was less likely to do so.

The British triple jumper Jonathan Edwards regularly used these high-weight, low-repetition weight workouts. The world record holder and Olympic champion was literally as light as a feather (he weighed in at his peak at 65kg), yet was incredibly powerful.

There’s also scientific support for this approach. Research by scientists from the University of Connecticut examined the hormonal responses and adaptation to resistance exercise and training ⁽¹⁾. They noted that high-volume, moderate-to-high-intensity weight training, using short rest intervals and stressing a large muscle mass, tended to produce the greatest acute hormonal elevations (notably testosterone and GH). In comparison low-volume, high-intensity resistance training methods using long rest intervals did not induce a similarly high hormonal response.

Sometimes, an athlete may wish to increase his or her lean muscle mass in order to enhance sports performance – rugby players and power athletes such as shot putters for example – and then high intensity ‘power’ workouts are entirely appropriate. The key point is that when planning a weight training schedule, you should not only take into account the perceived benefits of the session per se on muscle fibre power output, but also the hormonal effects it can have on influencing your weight.

Age, sex and hormone release

Is weight training mediated GH release affected by the age and sex of the athlete? Scientists from the University of North Carolina noted that GH secretion did vary with age and sex ⁽³⁾. They discovered that the magnitude of GH release was greater in young women than in young men and, perhaps less surprisingly, was reduced four- to sevenfold in older individuals compared with their younger counterparts. It seems that the late teens and early twenties appear to be a good time to boost lean muscle mass in female athletes, as their bodies appear more responsive to hormonally stimulated, weight-training induced muscle growth.

Age and GH secretion

Researchers have also observed an age-related drop in GH secretion, which is often correlated with deleterious health effects (although a cause and effect relationship has not been established). The good news is that while exercise interventions may not restore GH secretion to the levels observed in the young, exercise is still a robust stimulus for GH secretion. The implications of this for the master athlete are relatively obvious: where possible, intense weight training should be performed to naturally spike GH levels. This will contribute towards maintaining lean muscle mass, which declines significantly with age (see page 3 for suggested weight-training workouts and their hormonal responses).

Testosterone, age, sex and weight training

Research by Finnish scientists examined the relationship between age, sex and weight-training induced testosterone release ⁽⁴⁾. Forty-two subjects were divided into four groups:

1. 10 middle-aged men (average age 42);
2. 11 middle-aged women (average age 39);
3. 11 elderly men (average age 72);
4. 10 elderly women (average age 67).

The study consisted of six months of heavy resistance training and explosive exercises and the results were interesting. Functional training response was improved significantly; 1RM values increased in the middle-aged men by 27%, in the elderly men by 16% in the middle-aged women by 28% and in the elderly women by 24%. Training stimulated a significant testosterone response in both male groups, but not in the female groups. GH levels, on the other hand, increased in all groups, except the oldest women. Although this group failed to elicit a significant GH response to training, there are possible explanations (maybe they were not able to ‘push’ themselves to train intensely enough) and the overall findings demonstrate the value of weight training for a positive hormonal response in the older athlete.

Similar results were obtained by a study that examined the effects of heavy resistance training on the hormonal response patterns of younger (average age 32) and older (average age 62) men ⁽⁵⁾. Using four sets of 10 repetition squats with 90 seconds of rest between sets, the researchers found that squat strength and thigh muscle cross- sectional area increased for both groups.

Hormonally, the younger men demonstrated higher testosterone levels than the older men, both at rest and in response to exercise. However, with training, the older group demonstrated a significant increase in testosterone in response to exercise stress. They also experienced a significant decrease in resting cortisol. This overall response is ideal for increasing lean muscle mass; testosterone helps spike GH production and lower cortisol levels favour protein use for muscle building rather than energy purposes.

Response of elite athletes

Finally, some interesting Italian research looked at much more highly trained subjects, and studied the GH response induced by the total training programme of elite Italian track and field athletes ⁽⁶⁾. Ninety-nine Italian elite athletes from different disciplines (61 male, 38 female, aged 17 to 47) volunteered to participate in the investigation.

The scientists discovered that basal GH concentrations were significantly higher in females (6.2ng/ml) than in males (1.9ng/ml). These were negatively correlated with age and body mass index (BMI) – ie higher age and BMI predicted lower basal GH levels. GH release levels in response to exercise were also found to be significantly higher in females than in males performing the same discipline, in agreement with the North Carolina study above ⁽³⁾. It was also discovered that higher intensity workouts increased GH response (again in agreement with other studies).

Summary

Weight training (and exercise in general) has both outward and inward training effects. As a coach or athlete you may tend to think only of the former, ie the production of greater power-producing muscles, and not the latter. However, the design of a weight- training programme can have significant hormonal effects, which in turn can significantly affect the amount of lean muscle gains. This in turn can affect power-to-weight ratio, and be either negative or positive depending on your needs or activity. In the light of the research presented here, athletes would be well advised to also consider the latter.

John Shepherd MA is a specialist health, sport and fitness writer and a former international long jumper

References

1. Sports Med 2005; 35(4):339-61
2. McArdle, Katch and Katch (1994) Essentials of Exercise Physiology, Williams and Wilkins
3. Sports Med 2002; 32(15):987-1004
4. J Gerontol A Biol Sci Med Sci 2000; 55(2):B95-105
5. J. Appl. Physiol 1999; 87(3):982-992
6. J Endocrinol Invest 2004; 27(2):121-9